Circuit-breaker.



'No. 716,649. Patnted'Dec. 23; I902.

E. A. STEVENS.

CIRCUIT BREAKER.

(Application filed July 19. 1901.) (No Model.) 7 2 Sheets--Sheet (Nd Model.)

Patented Dec. 23, I902. E. A, STEVENS.

CIRCUIT BREAKER.

(Application filed July 19.41901 2 Sheets-Sheet 2.

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UNITED STATES PATENT OFFICE.

ERNEST A. STEVENS, OF CHICAGO, ILLINOIS,

CIRCUIT-BREAKER.

SPECIFICATION forming part of Letters Patent No. 716,649, dated December 23, 1902. Application filed July 19,1901. Serial No. 68,880. (No man.)

[ all whom, it may concern.-

Be it known that I, ERNEST A. STEVENS, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Circuit-Breakers; and I hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, which form part of this specification.

My invention relates to improvements in circuit-breakers, and especially to that class of circuit-breakers that are set into operation by the thermic efiect of an excessive electric current, whereby the circuit containing the circuit-breaker and the instrument which is to be protected thereby is opened as a result of the increased current above that which the circuit is designed to carry.

The object of my invention is to provide a circuit-breaker which will act automatically and promptly when the current flowing through the circuit exceeds a predetermined value. I 7

Another object of my invention is to provide a device which shall act promptly for the protection of the circuit, whether the current isincreased gradually or suddenly above a predetermined value.

Another object of my invention is to provide an automatic circuit-breaker which may be readily and easily inserted in the ordinary fuse-holder used in circuits that are designed to be protected by fuses and whereby the device may be readily removed for repairs or replaced by another similar device.

My invention is especially designed for the protection of telephone or other delicate instruments of like character against the increase of electric current from extraneous sources.

When an electric current of greater strength than is designed to be carried by the circuit in which telephone instruments are located is suddenly thrown upon the said circuit, the ordinary fuses are sufficient protection; but when such heavy currents are gradually introduced into such circuits it is a fact that the fuses designed to be destroyed when the current in the circuit is increased in increments of a very small ratio are not reliable, for then they will carry a much larger current than that for which they are designed, and for that reason other parts of the circuit, such as the delicate instruments, will be burned out before the fuse will separate and open the circuit and thus protect the instruments for which it is designed.

The gradually-increasing currents just described are known in the art as sneak-currents and are very difficult to guard against.

In my device the increased heat or thermic effect evolved by the abnormal currents is cumulative and is transmitted directly to a joint held together by a metal or solder designed to fuse at a low temperature until the accumulation of heat is sufficient to fuse the uniting medium, when the two parts of the circuit-breaker will be separated and the circuit thereby opened.

WVith these and other objects in view, which will be obvious to those skilled in the art from the description hereinafter, my invention consists in the several features, details of construction, and combinations of parts, which will first be described in connection with the accompanying drawings and then particularly pointed out in the appended claim.

In the drawings, Figure 1 is a side elevation of the preferred form of the device with the circuit closed between the two terminals thereof. Fig. 2 is a similar view with the circuit open. Fig. 3 is a plan view of the device as shown in Fig. 1. Fig. 4 is a section through line 4: 4 of Fig. 2. Fig. 5 is a modification of Fig. 1, showing a longer break when the circuit is opened. Fig. 6 is a plan view of the same. Fig. 7 is a side elevation of a modification of my device adapted to be introduced into a cut-out holder of a different type. Fig. 8 is a plan view of the same. Fig. 9 is an enlarged end elevation section ofFig. 7. Fig. 10 is another modification showing the device of Fig. 7 and the means by which it is introduced into a cut-out holder such as illustrated in Fig. 1. Fig. 11 is a plan View of the same. Fig. 12 is a bottom View of the insulating-plate, showing the terminals adapted to make contact with the clips on the fuseholder. Fig. 13 is a section through line 13 13 of Fig. 10.

In all of the views the same numerals indicate similar parts.

An ordinary fuse-holder 1, usually made of porcelain, is shown in the various figures.

The terminals 2 and 3 (shown in the modification of Fig. 7 as 2 and 3) are adapted to receive a circuit-protecting device, which may be a fuse-wire or my automatic circuitbreaker.

4 and 5 are the terminals of the circuit-protecting device. They are connected to the clamps 2 and To these latter terminals the circuit-wires are to be attached.

6 is a plate of insulating material, which may be made of mica, fiber, or hard rubber or similar suitable substances.

7 is a metal conductor fixed to the side of the plate 6 and adapted to support the insulating-block 8 by means of the screw 9.

The metal spool 10 is provided on its lower end with a threaded screw-terminal, which is adapted to be screwed into the insulatingblock 8 for the purpose of supporting the spool thereon.

The spool 10 is made, preferably, of brass or other diamagnetic metal and is provided on its top part with a smooth even surface 11, which is designed to be coated-over with a solder or other suitable cement which will flow at a low temperature.

12 is a resilient conductor attached to the terminal 14 of the plate 6. It has on its upper end a plate 13, which is designed to cover the top surface 11 of the spool. The surfaces 13 and 11 are designed to be soldered or cemented together by means of the solder,which is to be placed between the two surfaces.

15 is a terminal of the device, of which 7 is a conducting projection.

When the circuit is closed through the device,the parts are in the position shown in Fig. 1, the surfaces 13 and 11 being soldered together. The spool 10 is wound with a fine insulated resistance-wire, the inner end of which is connected to the metallic spool. The outer end is connected to the terminal 7 or to any part in metallic contact therewith. The circuit is completed through the device shown in Fig. 1 from the bindingscrew 4:, through the clip 2, the spring-wire 12, the surfaces 11 and 13, the body part of the spool 10, through the outer terminal on the said spool, to the terminal 7, through the clip 3, through the binding-screw 5.

The radiating-surfaces of the device are sufficient to disperse the heat as fast as it accumulates when the normal current is passing through the said device, but should 2. current greater than the normal pass through the device then the thermo or heating effect of the current would accumulate until the surfaces of the spool 10 would become sufficiently warm to melt or fuse the solder between the contacts 11 and 13, when the re silient effect of the conductor 12 would cause the said, surfaces to become separated and the conductor 2 would be thrown into the position shown in Fig. 2 and the circuit thereby opened. 7 The same principle of operation applies to all of the modifications shown.

Should it become desirable to unite the surfaces 11 and 13, so that they will be retained in the position which is shown in Fig. 1, all that is necessary is to connect the terminals 4 and 5 to a source of elecric current, such as a single cell of battery, and hold the surfaces 11 and 13 together until the solder is again melted, then still holding the surfaces together withdraw the current until the contact has so cooled that the solder has become set and the device is ready again for operation. This may be repeated indefinitely without destroying the useful effect of the device.

The modification of the device shown in Fig. 5 differs only from that shown in Fig. 1 in that the heating device or spool 10 and support are placed to one side of one of the terminals 15 instead of between the terminals 14 and 15, so that a longer spring-conductor 12 may be employed and a more extensive break between 11 and 13 may be made.

The modification of the device shown in Fig. 7 is made to be more readily adaptable to the peculiar fuse-holder clips 2 and 3, the sides of the supporting-plate being in a horizontal plane instead of a Vertical plane and the coil being supported on the side of the plate instead of its edge, the terminals 14 and 15 of the modification being perforated to admit the attaching terminal screws 2 and 3".

In all other respects the modifications are similar to the preferred form shown in Figs. 1, 2, 3, and 4.

My device is especially valuable because it is adapted to be inserted into the standard cut-out fixtures that are already in use. The certainty of its operation and the small energy lost by its resistance when in normal operation makes it especially valuable. The ease with which the device may be reset or adjusted and its adaptability to meet the conditions produce results that will be recognized as valuable by those skilled in the art.

It is apparent that many changes and modifications may be made differing from those shown in the drawings without departing from the gist and scope of my invention.

Having described my invention, what I claim as new and useful, and desire to secure by Letters Patent of the United States, is In an instrument, of the class described, the combination with a cut-out holder of, an insulating-plate, electric conducting-terminals thereon adapted to make contact with conducting-terminals of said holder, an insulated metallic spool on one of the metal terminals, a conductor adapted to be heated IIO by an abnormal current, sufficient to flow a In testimony that I claim the foregoing as sealing material, wound thereon, a movable my own I affix my signature in presence of conductor supported by the associated tertwo witnesses. lninal, a disk carried on the end of said con- 1 dnctor adapted to make contact with the head ERNEST STEVENS of said metallic spool, and a sealing material In presence ofadapted to hold the said disk normally in FOREE BAIN, contact with said spool. M. F. ALLEN. 

